1. Field of the Invention
This invention relates to vehicle suspension systems and, more particularly, to systems for causing the rear axles of a vehicle having a long wheel base (for example, cars, trucks, trailers, buses, heavy equipment, airplanes) to track around sharp corners.
2. Description of the Related Art
Prior art rear axle (see DEFINITIONS section) tracking systems have been disclosed in the U.S. Pat. No. 5,479,999 issued to the present inventor on Jan. 2, 1996 and entitled “Powered, Automatic, Self-Tracking System for the Rear Axles of Trucks, Trailers and Buses,” (the “'999 patent”) and U.S. Pat. No. 5,220,972 issued to the present inventor on Jun. 22, 1993 and entitled “Self-Tracking, Rear Vehicle Suspension System for Trucks, Trailers and Buses” (the “'972 patent”).
The '972 patent discloses an apparatus for permitting the self-tracking of rear axles through angling of torsion rods coupled with means for permitting lateral deflection of the suspension hardware employed on the vehicle (for example, widening of the spring hangers on a vehicle employing a leaf-spring type suspension). More particularly, the forward ends of each pair of laterally spaced torsion rods are moved inwardly toward each other to create separate reaction forces which cause the associated axle to pivot with respect to the vehicle centerline in a direction away from the turn during cornering. Consequently, the rear tires rotate closely along the turning path of the front tires such that the rear tires “track” around the corner. The more closely the rear tires track the front tires around the turn, the easier it is for the driver to safely negotiate the turn. For example, when the rear tires closely track the front tires then the vehicle can make turns without having to use more than a single lane of the roadway as drivers of such vehicles normally do when making turns.
The '999 patent discloses power controls which automatically respond to cornering of the vehicle by applying a controlled, measured force against selected points of the vehicle's suspension system which further assist in pivoting the rear axle(s) in the appropriate direction, thereby causing the respective rear tires to self-track into the turn, in both forward and reverse directions of travel.
The following published documents may also include helpful background information: (i) U.S. Pat. No. 5,242,131 (“Watts”); (ii) U.S. Pat. No. 3,516,625 (“Houser”); (iii) U.S. Pat. No. 6,029,931 (“Encarthe”); (iv) U.S. patent application 2010/0078517 (“Coles”); (v) U.S. Pat. No. 7,392,996 (“Mattocks”); (vi) U.S. Pat. No. 6,880,839 (“Keeler”); (vii) U.S. Pat. No. 6,293,570 (“570 Gottschalk”); and/or (viii) U.S. Pat. No. 6,007,078 (“078 Gottschalk”).
Description Of the Related Art Section Disclaimer: To the extent that specific publications are discussed above in this Description of the Related Art Section, these discussions should not be taken as an admission that the discussed publications (for example, published patents) are prior art for patent law purposes. For example, some or all of the discussed publications may not be sufficiently early in time, may not reflect subject matter developed early enough in time and/or may not be sufficiently enabling so as to amount to prior art for patent law purposes. To the extent that specific publications are discussed above in this Description of the Related Art Section, they are all hereby incorporated by reference into this document in their respective entirety(ies).